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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: noise.c,v 1.3 1998/01/12 16:46:19 mdw Exp $ |
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4 | * |
5 | * Collection of environmental noise |
6 | * |
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7 | * (c) 1998 EBI |
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8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of `become' |
13 | * |
14 | * `Become' is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * `Become' is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with `become'; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: noise.c,v $ |
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32 | * Revision 1.3 1998/01/12 16:46:19 mdw |
33 | * Fix copyright date. |
34 | * |
35 | * Revision 1.2 1997/08/20 16:19:57 mdw |
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36 | * Fix test for `/dev/random' so that it doesn't close `stdin' if it fails! |
37 | * |
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38 | * Revision 1.1 1997/08/07 09:45:26 mdw |
39 | * New source file added to acquire environmental noise and add it to the |
40 | * randomness pool (see `rand.c'). |
41 | * |
42 | */ |
43 | |
44 | /*----- Header files ------------------------------------------------------*/ |
45 | |
46 | /* --- ANSI headers --- */ |
47 | |
48 | #include <ctype.h> |
49 | #include <errno.h> |
50 | #include <stdio.h> |
51 | #include <stdlib.h> |
52 | #include <string.h> |
53 | #include <time.h> |
54 | |
55 | /* --- Unix headers --- */ |
56 | |
57 | #include <sys/types.h> |
58 | #include <sys/time.h> |
59 | |
60 | #include "config.h" |
61 | #if defined(HAVE_GETRUSAGE) |
62 | # include <sys/resource.h> |
63 | #elif defined(HAVE_VTIMES) |
64 | # include <sys/vtimes.h> |
65 | #endif |
66 | |
67 | #include <sys/wait.h> |
68 | |
69 | #include <fcntl.h> |
70 | #include <unistd.h> |
71 | |
72 | /* --- Local headers --- */ |
73 | |
74 | #include "noise.h" |
75 | #include "rand.h" |
76 | #include "utils.h" |
77 | |
78 | /*----- Main code ---------------------------------------------------------*/ |
79 | |
80 | /* --- @noise__shell@ --- * |
81 | * |
82 | * Arguments: @const char *cmd@ = pointer to a shell command |
83 | * |
84 | * Returns: --- |
85 | * |
86 | * Use: Adds the output of the shell command to the randomness pool. |
87 | * Some care is taken to do the Right Thing when running setuid. |
88 | */ |
89 | |
90 | static void noise__shell(const char *cmd) |
91 | { |
92 | int pfd[2]; |
93 | pid_t pid; |
94 | |
95 | /* --- Create a pipe for talking to the child --- */ |
96 | |
97 | if (pipe(pfd)) |
98 | return; |
99 | |
100 | /* --- Create the child process --- */ |
101 | |
102 | pid = fork(); |
103 | if (pid < 0) |
104 | return; |
105 | |
106 | if (pid == 0) { |
107 | int fd; |
108 | char *argv[] = { "/bin/sh", "-c", 0, 0 }; |
109 | char *env[] = { |
110 | "PATH=/bin:/usr/bin:/usr/ucb:/usr/etc:/sbin:/usr/sbin", |
111 | 0 |
112 | }; |
113 | |
114 | /* --- Become whoever I'm being run as --- */ |
115 | |
116 | setuid(getuid()); |
117 | |
118 | /* --- Close the old standard streams --- */ |
119 | |
120 | close(0); |
121 | close(1); |
122 | close(2); |
123 | |
124 | /* --- Set up stdin and stderr to be empty, and stdout as our pipe --- */ |
125 | |
126 | if (((fd = open("/dev/null", O_RDONLY)) != 0 && |
127 | (fd = dup2(fd, 0)) != 0) || |
128 | ((fd = dup2(pfd[1], 1)) != 1) || |
129 | ((fd = open("/dev/null", O_WRONLY)) != 2 && |
130 | (fd = dup2(fd, 2)) != 2)) |
131 | goto child_fail; |
132 | |
133 | /* --- Close the original pipe file descriptors --- */ |
134 | |
135 | close(pfd[0]); |
136 | close(pfd[1]); |
137 | burn(pfd); |
138 | |
139 | /* --- Now run the child process --- */ |
140 | |
141 | argv[2] = (char *)cmd; /* POSIX screwed up the prototype */ |
142 | execve("/bin/sh", argv, env); |
143 | |
144 | /* --- Something went horribly wrong --- */ |
145 | |
146 | child_fail: |
147 | _exit(127); |
148 | } |
149 | |
150 | /* --- Now read from the child until it's all done --- */ |
151 | |
152 | { |
153 | char buf[1024]; |
154 | ssize_t sz; |
155 | |
156 | close(pfd[1]); |
157 | for (;;) { |
158 | sz = read(pfd[0], buf, sizeof(buf)); |
159 | if (sz == 0 || (sz < 0 && sz != EINTR)) |
160 | break; |
161 | rand_add(buf, sz); |
162 | } |
163 | close(pfd[0]); |
164 | rand_add(pfd, sizeof(pfd)); |
165 | burn(buf); burn(pfd); |
166 | } |
167 | |
168 | /* --- The child should be dead now, so wait for it --- */ |
169 | |
170 | { |
171 | int st; |
172 | |
173 | wait(&st); |
174 | rand_add(&st, sizeof(st)); |
175 | rand_add(&pid, sizeof(pid)); |
176 | } |
177 | } |
178 | |
179 | /* --- @noise_acquire@ --- * |
180 | * |
181 | * Arguments: --- |
182 | * |
183 | * Returns: --- |
184 | * |
185 | * Use: Attempts to acquire an amount of random noise from the |
186 | * environment. A lot of it's not actually much good, but |
187 | * it's better than nothing. There's probably a bit or two's |
188 | * worth in each item which gets added. |
189 | */ |
190 | |
191 | void noise_acquire(void) |
192 | { |
193 | /* --- Try a real random number source --- * |
194 | * |
195 | * Some operating systems (notably Linux) provide a `/dev/random' which |
196 | * contains distilled random numbers from the outside world. |
197 | */ |
198 | |
199 | { |
200 | int fd; |
201 | int f; |
202 | unsigned char buff[64]; |
203 | ssize_t sz; |
204 | |
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205 | if ((fd = open("/dev/random", O_RDONLY)) >= 0 && |
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206 | (f = fcntl(fd, F_GETFL, 0)) >= 0 && |
207 | fcntl(fd, F_SETFL, f | O_NONBLOCK) >= 0 && |
208 | (sz = read(fd, buff, sizeof(buff))) > 0) { |
209 | rand_add(buff, sz); |
210 | burn(buff); |
211 | } |
212 | if (fd >= 0) |
213 | close(fd); |
214 | } |
215 | |
216 | /* --- Squeeze some entropy from the current time --- */ |
217 | |
218 | { |
219 | struct timeval tv; |
220 | clock_t c; |
221 | |
222 | gettimeofday(&tv, 0); |
223 | c = clock(); |
224 | rand_add(&tv, sizeof(tv)); |
225 | rand_add(&c, sizeof(c)); |
226 | burn(tv); burn(c); |
227 | } |
228 | |
229 | /* --- Try some commands which ask the outside world some questions --- */ |
230 | |
231 | noise__shell("ps auxww"); |
232 | noise__shell("ps -ef"); |
233 | noise__shell("df"); |
234 | /* @noise__shell("netstat -a");@ -- takes too long */ |
235 | |
236 | /* --- Get our resource usage to see if that's at all interesting --- */ |
237 | |
238 | #if defined(HAVE_GETRUSAGE) |
239 | { |
240 | struct rusage ru; |
241 | getrusage(RUSAGE_SELF, &ru); |
242 | rand_add(&ru, sizeof(ru)); |
243 | getrusage(RUSAGE_CHILDREN, &ru); |
244 | rand_add(&ru, sizeof(ru)); |
245 | burn(ru); |
246 | } |
247 | #elif defined(HAVE_VTIMES) |
248 | { |
249 | struct vtimes vt, vtc; |
250 | vtimes(&vt, &vtc); |
251 | rand_add(&vt, sizeof(vt)); |
252 | rand_add(&vtc, sizeof(vtc)); |
253 | burn(vt); burn(vtc); |
254 | } |
255 | #endif |
256 | |
257 | /* --- Squeeze some more entropy from the current time --- */ |
258 | |
259 | { |
260 | struct timeval tv; |
261 | clock_t c; |
262 | |
263 | gettimeofday(&tv, 0); |
264 | c = clock(); |
265 | rand_add(&tv, sizeof(tv)); |
266 | rand_add(&c, sizeof(c)); |
267 | burn(tv); burn(c); |
268 | } |
269 | |
270 | /* --- Done -- churn the random pool --- */ |
271 | |
272 | rand_churn(); |
273 | } |
274 | |
275 | /*----- That's all, folks -------------------------------------------------*/ |